JP6394740B2 - Magnetic field detector - Google Patents

Description

  The present invention relates to a magnetic field detection device that detects a minute magnetic field and the like.

  Recently, there is an increasing need for measuring weak magnetic fields such as biomagnetic field measurement, flaw detection measurement and nondestructive inspection.

  In the measurement of minute magnetic fields, the influence of environmental magnetic fields such as the geomagnetism that enters the magnetic field to be detected and the magnetic field generated by the measuring device becomes a problem. Various environmental magnetic field canceling techniques have been proposed to solve these problems. .

  According to Patent Document 1 (Japanese Patent Laid-Open No. 2009-297224), an environmental magnetic field detection sensor and a detection sensor are arranged in a plurality of coils for reducing the influence of an environmental magnetic field, and an object to be detected is excluded while eliminating the environmental magnetic field. The magnetic field is detected.

  According to Patent Document 2 (Japanese Patent Application Laid-Open No. 2012-152515), the output of a magnetic sensor that detects only the environmental magnetic field is calculated from the output of the magnetic sensor including the environmental magnetic field and the detection magnetic field to be detected. In this way, cancellation of the environmental magnetic field is realized, and a detection magnetic field to be detected is output. Here, a differential arithmetic circuit that performs a differential operation of a pair of differential operation units and an output of the pair of differential operation units that detect an environmental magnetic field that is an environmental magnetic field and a detection magnetic field that is a detection target, respectively. Requires three circuits.

  In general, a so-called temperature drift, which is a fluctuation in the output of the magnetic sensor due to a fluctuation in the environmental temperature of the magnetic sensor that detects the environmental magnetic field, may be a problem. In particular, when a magnetoresistive element is used as the magnetic field detecting element, output fluctuation (temperature drift) of the magnetic sensor is likely to occur due to environmental temperature fluctuation. This is because the resistance change rate of the magnetoresistive element varies with temperature.

JP 2009-297224 A JP 2012-152515 A

  The method of calculating a difference by calculation as in Patent Document 2 requires an electric calculation circuit, particularly a large number of differential calculation units, which is disadvantageous in terms of cost and downsizing of the sensor unit.

  Accordingly, an object of the present invention is to reduce the number of parts and the size of the differential operation unit.

  In order to achieve the above object, the present invention provides a first magnetic field generation unit having a first magnetic field generation conductor, a first magnetic field detection element, and a first magnetic field detection element according to an environmental magnetic field. A first feedback current is passed through the first magnetic field generating conductor so that the first magnetic field generating unit applies the first feedback current magnetic field in the direction opposite to the environmental magnetic field to the first magnetic field detecting element when the output is input. A first magnetic field detection unit having a second differential operation unit, a second magnetic field generation unit having a second magnetic field generation conductor through which a second current corresponding to the first feedback current flows, and a second magnetic field A second magnetic field detection unit having a detection element, and the second magnetic field generation unit applies a magnetic field in a direction opposite to the environmental magnetic field according to the second current to the second magnetic field detection element. The magnetic field detector is a magnetic field detector that detects a detected magnetic field.

  According to the present invention, since the calculation of the sensor output for eliminating the environmental magnetic field is unnecessary, the number of parts of the differential operation unit can be reduced and the size can be reduced. It is also possible to suppress the fluctuation (temperature drift) in the output of the magnetic field detection unit for the detection magnetic field due to the environmental temperature of the environmental magnetic field.

  In the present invention, the magnetic field generated by the first magnetic field generating conductor and the magnetic field generated by the second magnetic field generating conductor are parallel, and the first magnetic field detecting element and the second magnetic field detecting element are parallel. It is good also as a magnetic field detector arranged.

  According to the present invention, it is possible to make the magnetic field generated by the first magnetic field generating conductor and the magnetic field generated by the second magnetic field generating conductor equivalent to each other.

  In the present invention, the first magnetic field generating conductor is a first solenoid coil disposed away from the first magnetic field detecting element, and the second magnetic field generating conductor is separated from the second magnetic field detecting element. The first magnetic field detecting element is disposed in the first solenoid coil, the second magnetic field detecting element is disposed in the second solenoid coil, and the first magnetic field detecting element is disposed in the second solenoid coil. The magnetic field detection element and the second magnetic field detection element may be arranged in parallel so that the center line of the first solenoid coil and the center line of the second solenoid coil are parallel to each other.

  According to the present invention, since the first and second solenoid coils are individually arranged, the design is facilitated as compared with the integrated solenoid coil.

  In the present invention, the second magnetic field generation unit has a third magnetic field generation conductor, and the second magnetic field detection unit receives a second output corresponding to the detection magnetic field of the second magnetic field detection element. The second magnetic field generation unit includes a second differential operation unit that supplies a second feedback current to the second magnetic field generation unit so as to apply a magnetic field in the direction opposite to the detection magnetic field to the second magnetic field detection element. Is a magnetic field detection for generating a second current magnetic field corresponding to the second current flowing in the second magnetic field generating conductor and a second feedback current magnetic field corresponding to the second feedback current flowing in the third magnetic field generating conductor. It is good also as an apparatus.

  According to the present invention, it is possible to suppress the fluctuation (temperature drift) of the output of the magnetic field detection unit (second magnetic field detection unit) for the detection magnetic field caused by the change in the environmental temperature. Further, since the second feedback current magnetic field in the direction opposite to the detection magnetic field is generated by the second magnetic field generation unit, the operation area of the second magnetic field detection element is limited, and the resistance value of the second magnetic field detection element is reduced. Since the fluctuation due to temperature is suppressed, the linearity of the output voltage can be improved.

  In the present invention, the second magnetic field detection unit receives a second output corresponding to the detection magnetic field of the second magnetic field detection element, and applies a magnetic field in a direction opposite to the detection magnetic field to the second magnetic field detection element. A second differential operation unit that causes the second feedback current to flow through the second magnetic field generation unit to provide the second magnetic field generation unit, the second magnetic field generation unit including the second current flowing through the second magnetic field generation conductor and the second It is good also as a magnetic field detection apparatus which generates the magnetic field according to this feedback current.

  According to the present invention, the second magnetic field generation unit generates a magnetic field corresponding to the second current and the second feedback current flowing through the second magnetic field generating conductor, so that the number of parts can be reduced.

  Further, the first and second magnetic field detection elements may be magnetoresistive elements.

  Since the differential calculation for the sensor output for eliminating the environmental magnetic field is unnecessary, the number of parts of the differential calculation unit can be reduced and the sensor can be downsized.

It is explanatory drawing of the magnetic field detection apparatus of Embodiment 1. It is explanatory drawing of the magnetic field detection apparatus of Embodiment 2. It is the schematic diagram which showed the relationship between the form which implements this invention, and a magnetic field. FIG. 3 is a configuration diagram of a first magnetic field detection unit according to the first embodiment. It is a block diagram of the 3rd magnetic field generation conductor which the 2nd magnetic field detection part of Example 1 and a 2nd magnetic field generation part have. 1 is a structural diagram of a magnetic field detection apparatus of Example 1. FIG.

  FIG. 3 is a schematic diagram showing the relationship between the first magnetic field detection element 10, the second magnetic field detection element 20, the environmental magnetic field, and the detection magnetic field, which are prerequisites for implementing the present invention. The first magnetic field detection element 10 is disposed at a position where only the environmental magnetic field is detected. The second magnetic field detection element 20 is disposed at a position where the detection magnetic field can be detected, and exhibits a magnetosensitive characteristic for both the environmental magnetic field and the detection magnetic field. That is, the second magnetic field detection element 20 is disposed in the vicinity of the detection magnetic field generation source. Here, in the second magnetic field detection element 20, in order to detect only the detection magnetic field, it is necessary to reduce the detection amount by the environmental magnetic field. Since the environmental magnetic field is generally uniform, the detection amount of the first magnetic field detection element 10 according to the environmental magnetic field can be considered to be equivalent to the detection amount of the second magnetic field detection element 20 according to the environmental magnetic field. Therefore, in the second magnetic field detection element 20, the magnetic field corresponding to the amount detected by the first magnetic field detection element 10 is applied in the opposite direction to the environmental magnetic field of the second magnetic field detection element 20. It is possible to detect the detection magnetic field in a state where the influence of the environmental magnetic field is reduced. Here, the detection magnetic field is not limited to a DC magnetic field or an AC magnetic field. Further, the reverse direction with respect to the environmental magnetic field means the direction of the magnetic field having different signs for reducing the detection amount according to the environmental magnetic field of the first magnetic detection element 10 and the second magnetic detection element 20. In the following description, the reverse direction has the same meaning. The same applies to magnetic field detection elements other than the first magnetic detection element 10 and the second magnetic detection element 20.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined. Note that the drawings are schematic, and for convenience of explanation, the relationship between the thickness and the planar dimensions, and the ratio of the thickness between devices are within the range where the effect of this embodiment can be obtained, and the actual sensor structure. May be different.

(Embodiment 1)
FIG. 1 is a schematic diagram of a magnetic field detection device 1 according to the first embodiment. The magnetic field detection apparatus 1 includes a first magnetic field generation conductor 111 included in the first magnetic field generation unit 110, a first magnetic field detection element 10, a first differential operation circuit 211 included in the first differential operation unit 210, The first resistor 510, the second magnetic field generating conductor 121 included in the second magnetic field generating unit 120, the second magnetic field detecting element 20, and the detecting resistor 530 are provided. Here, the first magnetic field detection element 10, the first differential operation unit 210, and the first resistor 510 constitute the first magnetic field detection unit 410, and the second magnetic field detection element 20 and the detection resistor 530 are the first. 2 magnetic field detectors 420 are configured.

  One end of the first magnetic field generation conductor 111 included in the first magnetic field generation unit 110 is connected to the output terminal of the first differential operation circuit 211 included in the first differential operation unit 210. One end of the pair of input ends of the first differential arithmetic circuit 211 is connected to the other end of the first magnetic field detection element 10 having one end connected to the first potential (Vc). . The other input terminal of the pair of input terminals of the first differential arithmetic circuit 211 is connected to the third potential (Gnd). The other end of the first magnetic field detection element 10 is connected to the other end of the first resistor 510 whose one end is connected to the second potential (−Vc). The other end of the first magnetic field generation conductor 111 is connected to one end of a second magnetic field generation conductor 121 included in the second magnetic field generation unit 120. The other end of the second magnetic field generating conductor 121 is connected to a third potential (Gnd). The other end of the second magnetic field detection element 20 whose one end is connected to the first potential (Vc) is connected to one end of the detection resistor 530. The other end of the detection resistor 530 is connected to the second potential (−Vc). Here, the other end of the first magnetic field detection element 10 outputs a first output, and the other end of the second magnetic field detection element 20 outputs a second output.

  The first magnetic field detection unit disposed in the vicinity of the first magnetic field generation conductor 111 of the first magnetic field generation unit 110 at the input terminal of the first differential operation unit 210 provided in the first magnetic field detection unit 410. The first magnetic field generator 110 has a first feedback current that is an output of the first differential operation unit 210 so that the first output of the element 10 is input and fluctuations in the first output are reduced. The first magnetic field generating conductor 111 flows into the first magnetic field generating conductor 111, and the first magnetic field generating conductor 111 generates a first feedback current magnetic field in a direction opposite to the environmental magnetic field. That is, the first differential operation unit 210 included in the first magnetic field detection unit 410 is configured so that a substantially uniform environmental magnetic field such as terrestrial magnetism or an ambient environmental magnetic field is applied to the first magnetic field detection element 10 in the environment. A first feedback current is passed from the first differential operation unit 210 to the first magnetic field generating conductor 111 so as to reduce the magnetic field, and the first feedback current magnetic field in the opposite direction to the environmental magnetic field is used as the first magnetic field. It operates to be applied to the detection element 10. Therefore, since the influence of the environmental magnetic field is reduced by the first feedback current magnetic field that is in the opposite direction to the environmental magnetic field due to the first feedback current, fluctuations in the first output of the first magnetic field detection element 10 are reduced. The That is, the first magnetic field generator 110 generates a first feedback current magnetic field in the opposite direction to the environmental magnetic field by the first feedback current corresponding to the environmental magnetic field. Hereinafter, the first magnetic field generation unit 110 and the first magnetic field detection unit 410 will be described.

  The first magnetic field generation unit 110 has a first magnetic field generation conductor 111. If the first magnetic field generating conductor 111 gives a first feedback current magnetic field in the opposite direction to the environmental magnetic field generated by the first feedback current to the first magnetic detection element 10, its shape and The material is not particularly limited. For example, as long as the first magnetic field detection element 10 has a shape extending in one direction, the first magnetic field generating conductor 111 may be a linear conductor, and the first magnetic field detection element 10 is wound around the first magnetic field detection element 10. A solenoid-shaped conductor may be used. The first magnetic field generating conductor 111 may be insulated from the first magnetic field detection element 10 and may be formed integrally with the first magnetic field detection element 10, and is arranged apart from the first magnetic field detection element 10. In addition, it may be formed in a solenoid shape so as to surround the first magnetic field detection element 10 or may be formed in a linear shape. The first magnetic field generation unit 110 may have a configuration in which one end of the first magnetic field generation conductor 111 is connected to the output end of the first differential operation unit 210, and one end of the first magnetic field generation conductor 111. The other end of the first field effect transistor (not shown) whose one end of the non-control end is connected to the first potential (Vc) is connected, and the output of the first differential operation unit 210 is the first. It is good also as a structure connected to the control end of this field effect transistor (not shown). When one end of the first magnetic field generating conductor 111 is connected to the output terminal of the first differential operation unit 210, the output from the output terminal of the first differential operation unit 210 becomes the first feedback current. When the output of the first differential operation unit 210 is connected to the control terminal of a first field effect transistor (not shown), the output from the output terminal of the first differential operation unit 210 is the field effect transistor ( The current flowing through the first magnetic field generating conductor 111 connected to the other end of the non-control end corresponding to the signal at the control end is controlled as the first feedback current. Further, instead of the first field effect transistor (not shown), a bipolar transistor, an electrostatic induction transistor, or the like may be applied.

  The first differential operation unit 210 included in the first magnetic field detection unit 410 includes a first differential operation circuit 211. The first output which is the output of the first magnetic field detection element 10 is input to one input terminal of the pair of input terminals of the first differential arithmetic circuit 211, and the other input terminal is connected to the third potential (Gnd). )It is connected to the. Further, when a third magnetic field detection element (not shown) is present, the other end and one end of the third magnetic field detection element (not shown) are connected to the second potential (−Vc). The other end of the resistor (not shown) may be input to the other input terminal of the first differential circuit 211. Also, the first output which is the output of the first magnetic field detection element 10 is input to one input terminal of the pair of input terminals of the first differential arithmetic circuit 211, and the third potential is input to the other input terminal. (Gnd) and the other end and one end of the third magnetic field detection element (not shown) are connected to one input end of the pair of input ends of the second differential arithmetic circuit (not shown). The other end of a third resistor (not shown) connected to the second potential (−Vc) is input, and the other input end is connected to the third potential (Gnd). The outputs of the first differential arithmetic circuit 211 and the second differential arithmetic circuit (not shown) are respectively input to a pair of input terminals of a third differential arithmetic circuit (not shown). May be configured to operate so that the first feedback current flows through the first magnetic field generator 110. The first magnetic field detection element 10 to which the environmental magnetic field is applied and the third magnetic field detection element (not shown) are preferably different in sign of the rate of change in resistance value. Since the sign of the rate of change of the resistance value is different, the output of the first differential operation unit 210 can be increased, so that the detection accuracy of the environmental magnetic field can be increased.

  The first magnetic field detection unit 410 includes the first magnetic field detection element 10 and is disposed in a place that is affected by the first feedback current magnetic field that is in the opposite direction to the environmental magnetic field generated by the first feedback current. Is done. Further, the first magnetic field detection unit 410 may include third to fifth magnetic field detection elements (not shown). Here, the first magnetic field detection element 10 and the third to fifth magnetic field detection elements (not shown) are in the opposite direction to the environmental magnetic field generated by the first feedback current generated by the first magnetic field generation unit 110. It arrange | positions so that it may receive to the influence of a 1st feedback current magnetic field. In this case, the first connection point where the first magnetic field detection element 10 and the third magnetic field detection element (not shown) are connected, the fourth magnetic field detection element (not shown), and the fifth magnetic field detection. You may connect the 2nd connection point with which the element (not shown) was connected with the input terminal of a pair of 1st differential calculating part 210, respectively. As described above, when the first magnetic field detection element 10 and the third to fifth magnetic field detection elements (not shown) connected in a so-called full bridge are used, the environmental magnetic field is reduced, that is, The first differential operation unit 210 operates so that the potential difference between the first connection point and the second connection point becomes zero. That is, the first differential operation unit 210 operates so as to flow the first feedback current through the first magnetic field generating conductor 111. Therefore, the first magnetic field detection element 10 and the third to fifth magnetic field detection elements (not shown) are provided with the first feedback current magnetic field that is in the opposite direction to the environmental magnetic field due to the first feedback current. The environmental magnetic field is reduced. The first magnetic field detection element 10 and the third to fifth magnetic field detection elements (not shown) are preferably formed integrally. Further, one to three magnetic field detection elements among the third to fifth magnetic field detection elements (not shown) may be used as resistors. The first magnetic field detecting element 10 and the third to fifth magnetic field detecting elements (not shown) are an AM (anisotropic) magnetoresistive element, an SV (spin valve) giant magnetoresistive element, a tunnel type. Examples thereof include a magnetoresistive element such as a magnetoresistive element, and a Hall element.

  Here, as shown in FIG. 1, the other end of the first magnetic field detecting element 10 having one end connected to the first potential (Vc) and one end connected to the second potential (−Vc). When connected to the other end of the first resistor 510, the first output output from the other end of the first magnetic field detection element 10 and the third potential (Gnd) are the first differential. Each is input to the input terminal of the arithmetic unit 210. The output end of the first differential operation unit 210 is input to one end of the first magnetic field generation conductor 111 included in the first magnetic field generation unit 110, and the other end of the first magnetic field generation conductor 111 is the first end. 3 is connected to the other end of the second magnetic field generating conductor 121 connected to the potential of 3 (Gnd). The first magnetic field detecting element 10 disposed in the vicinity of the first magnetic field generating conductor 111 is affected in accordance with the environmental magnetic field of the environment, and the first output is reduced so as to reduce the fluctuation of the first output as its output. A first feedback current magnetic field in a direction opposite to the environmental magnetic field due to the feedback current is applied to the first magnetic field detection element 10. That is, the first feedback current magnetic field in the opposite direction to the environmental magnetic field due to the first feedback current that reduces the environmental magnetic field is opposite to the environmental magnetic field due to the second current flowing in the second magnetic field generating conductor 121. Since the second current magnetic field is applied to the first and second magnetic field detection elements (10, 20), respectively, the first and second magnetic fields due to the environmental magnetic field of the first and second magnetic field detection elements (10, 20) are provided. The resistance change ΔR of the magnetic field detection elements (10, 20) is controlled to be always zero with respect to a uniform environmental magnetic field. Note that the other end of the first magnetic field generating conductor 111 is connected to the other end of the second magnetic field generating conductor 121 whose one end is connected to the third potential (Gnd). And the second current are the same. Since ΔR is zero, there is almost no change in temperature of ΔR, so that it is possible to reduce output fluctuations (temperature drift) due to the temperature of ΔR of the environmental magnetic field. In particular, when the first and second magnetic field detection elements (10, 20) are magnetoresistive elements such as AM magnetoresistive elements, SV giant magnetoresistive elements, tunnel magnetoresistive elements, the magnetoresistive elements depend on temperature. Since the fluctuation of the resistance value is large, it is important to reduce the fluctuation of the output (temperature drift).

  Note that although the second potential is described as −Vc and the third potential is described as Gnd, the present invention is not limited to this, and the second potential may be Gnd and the third potential may be Vc / 2.

  In addition, it is preferable that the resistance value of the 1st resistance 510 and the 1st magnetic field detection element 10 in case an environmental magnetic field is substantially 0 is equivalent, and the 1st magnetic field detection element 10 and the 3rd-5th magnetic field. The resistance values of the detection elements (not shown) are preferably equal.

  The second magnetic field detection unit 420 includes a second magnetic field detection element 20 and a detection resistor 530. Therefore, the second magnetic field detection element 20 can detect a detection magnetic field generated in the vicinity of the second magnetic field detection element 20. Here, the detection magnetic field is a magnetic field that does not directly affect the first magnetic field detection element 10. Therefore, the first magnetic field detection unit 410 and the second magnetic field detection unit 420 are arranged apart from each other so as not to be affected by the detection magnetic field. A second magnetic field generation unit 120 is disposed in the vicinity of the second magnetic field detection element 20. A second current corresponding to the first feedback current flows through the second magnetic field generation unit 120, and the second magnetic field generation unit generates a second current magnetic field having a direction opposite to the environmental magnetic field. In other words, the second current magnetic field that is opposite to the environmental magnetic field generated by the second magnetic field generation unit 120 according to the first feedback current is a magnetic field that is opposite to the environmental magnetic field, and is affected by the environmental magnetic field. Is reduced. Therefore, the second magnetic field detection element 20 can detect the detection magnetic field in a state where the influence of the environmental magnetic field is reduced. Hereinafter, the second magnetic field generation unit 120 and the first magnetic field detection unit 420 will be described.

  The second magnetic field generation unit 120 has a second magnetic field generation conductor 121. As long as the second magnetic field generating conductor 121 gives the second magnetic field to the second magnetic detection element 20 in the opposite direction to the environmental magnetic field generated by the second current, the shape and material thereof are There is no particular question. For example, as long as the second magnetic field detection element 20 has a shape extending in one direction, the second magnetic field generating conductor 121 may be a linear conductor or a solenoid-shaped conductor. Further, the second magnetic field generating conductor 121 may be insulated from the second magnetic field detection element 20 and formed integrally with the second magnetic field detection element 20, and is disposed apart from the second magnetic field detection element 20. In addition, it may be formed in a solenoid shape so as to surround the second magnetic field detection element 20, or may be formed in a linear shape. The second magnetic field generation unit 120 may have a configuration in which one end of the second magnetic field generation conductor 121 is connected to the end of the first magnetic field generation conductor 111 via a conductor. The other end of a second field effect transistor (not shown) whose one end of the non-control end is connected to the first potential (Vc) is connected to one end of the generation conductor 121, and The output end (the output end of the first magnetic field generating conductor 111) may be connected to the control end of the second field effect transistor (not shown). When one end of the second magnetic field generating conductor 121 is connected to the end of the first magnetic field generating conductor 111 via the conductor, the first feedback current and the second current are the same. When the output terminal of the first magnetic field generation unit 110 (the output terminal of the first magnetic field generation conductor 111) is connected to the control terminal of a second field effect transistor (not shown), the first magnetic field generation unit 110 is connected. The output from the output terminal (the output terminal of the first magnetic field generating conductor 111) controls the control terminal of the second field effect transistor (not shown), and the other terminal of the non-control terminal according to the signal of the control terminal The current flowing through the second magnetic field generating conductor 121 connected to the second current is the second current. Further, a bipolar transistor, an electrostatic induction transistor, or the like may be applied instead of the second field effect transistor (not shown). Note that the first feedback current magnetic field that is opposite to the environmental magnetic field generated by the first magnetic field generation unit 110 by the first feedback current and the environment generated by the second magnetic field generation unit 120 by the second current are generated. In order to make the second current magnetic field opposite to the magnetic field the same magnetic field, the second magnetic field generator 120 preferably has a structure equivalent to that of the first magnetic field generator 110. In particular, it is preferable that the first magnetic field generating conductor 111 and the second magnetic field generating conductor 121 have an equivalent structure. In particular, the magnetic field generated by the magnetic field generating conductor 111 and the magnetic field generated by the second magnetic field generating conductor 121 are preferably parallel.

  The second magnetic field detection unit 420 includes the second magnetic field detection element 20 and is disposed at a location that is affected by the second current magnetic field. The second magnetic field detection unit 420 may include sixth to eighth magnetic field detection elements (not shown). Here, the second magnetic field detection element 20 and the sixth to eighth magnetic field detection elements (not shown) are arranged so as to be affected by the second current magnetic field generated by the second magnetic field generation unit 120. . In this case, a third connection point where the second magnetic field detection element 20 and the sixth magnetic field detection element (not shown) are connected, a seventh magnetic field detection element (not shown), and an eighth magnetic field detection. You may connect the 4th connection point with which the element (not shown) was connected with the input terminal of a pair of 3rd differential calculating part (not shown), respectively. Thus, when the so-called full-bridge connected second magnetic field detecting element 20 and sixth to eighth magnetic field detecting elements (not shown) are used, the third connecting point and the fourth connecting point are used. It is possible to detect the detection magnetic field from the potential difference between the two. Further, since the full bridge connection is used, the output can be increased. In addition, the magnetic field generated in the vicinity of the second magnetic field detection unit 420 is a magnetic field that combines both the environmental magnetic field and the second current magnetic field, and the influence of the environmental magnetic field is reduced. Not too long. Therefore, the second magnetic field detecting element 20 and the sixth to eighth magnetoresistive elements (not shown) can detect the detected magnetic field in a state where the influence of the environmental magnetic field is reduced. The second magnetic field detection element 20 and the sixth to eighth magnetic field detection elements (not shown) are preferably formed integrally. Further, one to three magnetic field detection elements among the sixth to eighth magnetic field detection elements (not shown) may be used as resistors. The second magnetic field detection element 20 and the sixth to eighth magnetic field detection elements (not shown) are magnetoresistive elements such as AM magnetoresistive elements, SV giant magnetoresistive elements, tunnel magnetoresistive elements, Examples include a Hall element. It should be noted that a magnetic field equivalent to the first current magnetic field that is opposite to the environmental magnetic field generated by the first feedback current and the second current magnetic field that is opposite to the environmental magnetic field generated by the second current. In order to be affected, the second magnetic field detector 420 preferably has a structure equivalent to that of the first magnetic field detector 410. In particular, it is preferable that the first magnetic field detection element 10 and the second magnetic field detection element 20 have an equivalent structure. The same applies to the case where there are a plurality of magnetic field detection elements, and the second magnetic field detection unit 420 preferably has the same structure and arrangement of magnetic field detection elements as the first magnetic field detection unit 410. In particular, the second magnetic field detector 420 and the first magnetic field detector 410 are preferably arranged in parallel.

  The second magnetic field detection unit 420 may include a third differential operation unit (not shown), and the third differential operation unit (not shown) includes a seventh differential operation circuit (not shown). (Not shown). Here, the second output which is the output of the second magnetic field detection element 20 is input to one input terminal of the pair of input terminals of the seventh differential operation circuit (not shown), and the other end is the first input terminal. 3 may be connected to the potential (Gnd). In addition, when there is a sixth magnetic field detection element (not shown), the other end and one end of the sixth magnetic field detection element (not shown) are connected to the second potential (−Vc). The connection end to which the other end of the resistor (not shown) is connected may be connected to the other input end of the seventh differential circuit (not shown). Also, the second output, which is the output of the second magnetic field detection element 20, is input to one input terminal of a pair of input terminals of a seventh differential operation circuit (not shown), and the other input terminal is connected to the other input terminal. A third potential (Gnd) is connected, and one end of a pair of input ends of an eighth differential arithmetic circuit (not shown) is connected to the other end of the sixth magnetic field detecting element (not shown). A connection end connected to the other end of a fourth resistor (not shown) whose one end is connected to the second potential (−Vc) is connected, and a third potential (Gnd) is connected to the other input end. The outputs of a seventh differential arithmetic circuit (not shown) and an eighth differential arithmetic circuit (not shown) are respectively connected to a pair of input terminals of a ninth differential arithmetic circuit (not shown). The output of the ninth differential operation circuit (not shown) may be used as the output of the third differential operation unit (not shown). The second magnetic field detection element 20 to which the environmental magnetic field is applied and the sixth magnetic field detection element (not shown) preferably have different signs of the rate of change in resistance value. Since the sign of the rate of change of the resistance value is different, the output of the third differential operation unit (not shown) can be increased, so that the detection accuracy of the environmental magnetic field can be increased.

  Here, as shown in FIG. 1, the other end of the second magnetic field detection element 20 having one end connected to the first potential (Vc) is detected with one end connected to the second potential (−Vc). The other end of the resistor 530 is connected. Therefore, an output corresponding to the detected magnetic field can be obtained from the other end of the detection resistor 530. When a third differential operation unit (not shown) exists, the output of the third differential operation unit (not shown) is an output corresponding to the detected magnetic field.

  Note that although the second potential is described as −Vc and the third potential is described as Gnd, the present invention is not limited to this, and the second potential may be Gnd and the third potential may be Vc / 2.

  Note that the resistance values of the first magnetic field detection element 10 and the second magnetic field detection element 20 when the environmental magnetic field is approximately 0 are preferably equal, and the second magnetic field detection element 20 and the sixth to eighth magnetic field detection elements 20 are preferably the same. The resistance values of the magnetic field detecting elements (not shown) are preferably equal.

  As in the prior art, in the method of calculating the difference between the outputs of the magnetic field detectors by calculation in order to reduce the influence of the environmental magnetic field, the magnetic field detectors corresponding to the first and second magnetic field detectors (10, 20) Two differential operation units that output outputs and a differential operation unit that outputs the differential of the outputs of the differential operation units are required. On the other hand, in the first embodiment, since the same function can be obtained only by the first differential operation unit 210 included in the first magnetic field detection unit 410, the number of parts of the differential operation unit can be reduced and the size can be reduced. It has become. The same applies even if a third differential operation unit (not shown) exists. That is, conventionally, a differential operation unit that performs a differential operation on the outputs of the first and third differential operation units is necessary, but this embodiment is not necessary.

  In the first embodiment, when detecting the detected magnetic field, the magnetic field detection unit for detecting the environmental magnetic field (first magnetic field detection unit 410) and the magnetic field detection for the detection magnetic field are detected by the output of the first differential operation unit 210. The first feedback current magnetic field and the second magnetic field generator 120 generated by the first magnetic field generator 110 in the opposite direction to the environmental magnetic field that is considered to be substantially uniform in each of the units (second magnetic field detector 420). By forming a current feedback loop that gives a second current magnetic field that generates a fluctuation in the output of the magnetic field detection unit for the detection magnetic field (second magnetic field detection unit 420) due to a change in the environmental temperature of the environmental magnetic field ( (Temperature drift) can be reduced.

(Embodiment 2)
FIG. 2 is a schematic diagram of the magnetic field detection device 2 of the second embodiment. The magnetic field detection device 2 includes a first magnetic field generation conductor 111 included in the first magnetic field generation unit 110, a first magnetic field detection element 10, a first differential operation circuit 211 included in the first differential operation unit 210, The first resistor 510, the second magnetic field generation conductor 121 included in the second magnetic field generation unit 120, the third magnetic field generation conductor 122, the second magnetic field detection element 20, and the second differential operation unit 220 include 4 differential operation circuit 221, second resistor 520, and detection resistor 540. Here, the first magnetic field detection element 10, the first differential operation unit 210, and the first resistor 510 constitute a first magnetic field detection unit 410, and the second magnetic field detection element 20 and the second differential field The calculation unit 220, the second resistor 520, and the detection resistor 540 constitute a second magnetic field detection unit 420. The connection relationship is shown below.

  One end of the first magnetic field generation conductor 111 included in the first magnetic field generation unit 110 is connected to the output terminal of the first differential operation circuit 211 included in the first differential operation unit 210. One end of the pair of input ends of the first differential arithmetic circuit 211 is connected to the other end of the first magnetic field detection element 10 having one end connected to the first potential (Vc). . The other input terminal of the pair of input terminals of the first differential arithmetic circuit 211 is connected to the third potential (Gnd). The other end of the first magnetic field detection element 10 is connected to the other end of the first resistor 510 whose one end is connected to the second potential (−Vc). The other end of the first magnetic field generation conductor 111 is connected to one end of a second magnetic field generation conductor 121 included in the second magnetic field generation unit 120. The other end of the second magnetic field generating conductor 121 is connected to a third potential (Gnd). The other end of the second magnetic field detection element 20 whose one end is connected to the first potential (Vc) is one of a pair of input ends of the fourth differential operation circuit 221 included in the second differential operation unit 220. Is connected to the input terminal. The other input terminal of the pair of input terminals of the fourth differential arithmetic circuit 221 is connected to the third potential (Gnd). The other end of the second magnetic field detection element 20 is connected to the other end of the second resistor 520 whose one end is connected to the second potential (−Vc). The output terminal of the fourth differential arithmetic circuit 221 is connected to one end of the detection resistor 540. The other end of the detection resistor 540 is connected to one end of the third magnetic field generating conductor 122. The other end of the third magnetic field generating conductor 122 is connected to a third potential (Gnd). Here, the other end of the first magnetic field detection element 10 outputs a first output, and the other end of the second magnetic field detection element 20 outputs a second output. The difference from the first embodiment is that the second magnetic field detection unit 420 includes a second differential operation unit 220, and the second magnetic field generation unit 120 includes a third magnetic field generation conductor 122. A current feedback loop is formed with respect to the detected magnetic field detected by the second magnetic field detector 420. Since other configurations are the same as those of the first embodiment, the second magnetic field generation unit 120 and the second magnetic field detection unit 420 will be described below. A description of a configuration equivalent to that of the first embodiment is omitted.

  The second magnetic field detection unit 420 includes a second differential operation unit 220, and the second differential operation unit 220 includes a fourth differential operation circuit 221. Here, the second output which is the output of the second magnetic field detection element 20 is input to one input terminal of the pair of input terminals of the fourth differential arithmetic circuit 221, and the other input terminal is the third input terminal. It is connected to a potential (Gnd). In addition, when a sixth magnetic field detection element (not shown) is present, the other end and one end of the sixth magnetic field detection element (not shown) are connected to the second potential (−Vc). A connection end to which the other end of the resistor (not shown) is connected may be connected to the other input end of the fourth differential circuit 221. In addition, the second output which is the output of the second magnetic field detection element 20 is input to one input terminal of the pair of input terminals of the fourth differential arithmetic circuit 221, and the third potential is input to the other input terminal. (Gnd) is connected, and the other end and one end of the sixth magnetic field detecting element (not shown) are connected to one input end of the pair of input ends of the fifth differential arithmetic circuit (not shown). A connection terminal connected to the other end of a third resistor (not shown) connected to the second potential (−Vc), a third potential (Gnd) connected to the other input terminal, The outputs of the fourth differential arithmetic circuit 221 and the fifth differential arithmetic circuit (not shown) are respectively input to a pair of input terminals of six differential arithmetic circuits (not shown), and the sixth differential arithmetic circuit An output terminal of an arithmetic circuit (not shown) may be connected to one end of the detection resistor 540. The second magnetic field detection element 20 to which the environmental magnetic field is applied and the sixth magnetic field detection element (not shown) preferably have different signs of the rate of change in resistance value. Since the sign of the rate of change of the resistance value is different, the output of the second differential operation unit 220 can be increased, so that the detection accuracy of the environmental magnetic field can be increased.

  Here, as shown in FIG. 2, one end of the third magnetic field generating conductor 122 included in the second magnetic field generation unit 120 is connected to the output terminal of the second differential operation unit 220. The second feedback current flows through the detection resistor 540 connected to the other end of the 540. Therefore, an output corresponding to the detected magnetic field can be obtained from one end of the detection resistor 540. Further, the output terminal of the second differential operation unit 220 and the control terminal of a third field effect transistor (not shown) in which one end of the non-control terminal is connected to the first potential (Vc) are connected, One end of the detection resistor 540 may be connected to the other end of the non-control end of a third field effect transistor (not shown). In this case, the output from the output end of the second differential operation unit 220 controls the control end of the third field effect transistor (not shown), and the other end of the non-control end according to the signal at the control end. The current flowing through the connected detection resistor 540 becomes the second feedback current. Further, a bipolar transistor, an electrostatic induction transistor, or the like may be applied instead of the third field effect transistor (not shown). It is also possible to adopt a configuration in which the first feedback current and the second current individually flow through different conductors. When one end of the first magnetic field generating conductor 111 and the other end of the second magnetic field generating conductor 121 having one end connected to Gnd are connected by a conductor, the first feedback current and the second current are made the same. be able to.

  In addition, the other end of the detection resistor 540 is connected to one end of the third magnetic field generating conductor 122 included in the second magnetic field generation unit 120, so that the second differential operation unit 220 can output the second When the second feedback current flows through the third magnetic field generating conductor 122 included in the magnetic field generation unit 120, the second feedback current magnetic field in the direction opposite to the detection magnetic field for reducing the detection magnetic field is changed to the second magnetic field generation unit 120. Occurs. Here, the reverse direction with respect to the detected magnetic field means the direction of the magnetic field having a different sign for reducing the detection amount according to the detected magnetic field of the second magnetic detection element 20. The same applies to magnetic field detection elements other than the second magnetic detection element 20 included in the second magnetic field detection unit 420. That is, the second differential operation unit 220 operates so as to cause the second feedback current to flow through the third magnetic field generating conductor 122. Therefore, the second magnetic field generation unit 120 responds to the second current magnetic field corresponding to the second current flowing through the second magnetic field generation conductor 121 and the second feedback current flowing through the third magnetic field generation conductor 122. A second feedback current magnetic field is generated. Therefore, the second feedback current magnetic field in the direction opposite to the detection magnetic field according to the second feedback current for reducing the detection magnetic field and the environmental magnetic field in the direction opposite to the first feedback current for reducing the environmental magnetic field. A second current magnetic field is applied to the second magnetic field detection element 20.

  Note that the other end of the detection resistor 540 may be connected to one end of the second magnetic field generating conductor 121, and the second current and the second feedback current may flow through the second magnetic field generating conductor 121. In this case, a magnetic field corresponding to the second current flowing through the second magnetic field generating conductor 121 and the second feedback current is generated. Therefore, the number of parts can be reduced. Further, if the first magnetic field generating conductor 111 is a solenoid shape, the second magnetic field generating conductor 121 can have a solenoid shape equivalent to that of the first magnetic field generating conductor 111. Further, by using the same material for the first magnetic field generating conductor 111 and the second magnetic field generating conductor 121, it is not necessary to use the third magnetic field generating conductor 122, so that the dependency of the temperature coefficient can be further reduced. become. Further, since it is not necessary to consider the interaction between the respective magnetic fields generated by the second magnetic field generating conductor 121 and the third magnetic field generating conductor 122, the detection magnetic field region can be widened.

  Note that although the second potential is described as −Vc and the third potential is described as Gnd, the present invention is not limited to this, and the second potential may be Gnd and the third potential may be Vc / 2.

  As described above, in the second embodiment, when detecting the environmental magnetic field detection magnetic field, a magnetic field corresponding to the second feedback current and the second current is applied to the second magnetic field detection unit 420. Therefore, since the second feedback current that reduces the detected magnetic field according to the output of the second differential operation unit 220 flows to the second magnetic field generation unit 120 to form a current feedback loop, the second magnetic field Since the resistance change ΔR of the second magnetic field detection element 20 included in the detection unit 420 is controlled to be always zero with respect to the detection magnetic field, the second magnetic field detection caused by the environmental temperature compared to the first embodiment. It is possible to detect the detected magnetic field while suppressing output fluctuation (temperature drift) with respect to the detected magnetic field of the unit 420. In addition, since the current feedback loop is formed, the operation region of the second magnetic field detection element 20 included in the second magnetic field detection unit 420 is limited, and the variation due to the temperature of the resistance change ΔR is suppressed. The linearity of the output of the second magnetic field detector 420 can also be improved.

Example 1
FIG. 4 is a configuration diagram of the first magnetic field detection unit 410 according to the first embodiment. The magnetic field detection unit 410 includes a first differential operation circuit 211, a first magnetoresistive element 10, and third to fifth magnetoresistive elements (30, 40, 50). Here, the first magnetoresistive element 10 and the third to fifth magnetoresistive elements (30, 40, 50) are SV giant magnetoresistive elements, which are formed on a substrate, and have a free layer, a conductive layer, The pinned layer is laminated. One end of the first magnetoresistive element 10 is connected to the first potential (Vc), the other end of the first magnetoresistive element 10 and the other end of the third magnetoresistive element 30 are connected, and a third magnetism One end of the resistance element 30 is connected to the third potential (Gnd). One end of the fourth magnetoresistive element 40 is connected to the first potential (Vc), the other end of the fourth magnetoresistive element 40 is connected to the other end of the fifth magnetoresistive element 50, and the fifth magnetism One end of the resistance element 50 is connected to the third potential (Gnd). Here, the first magnetoresistive element 10 and the third to fifth magnetoresistive elements (30, 40, 50) are arranged on the same plane, and the first magnetoresistive element 10 and the third magnetoresistive element 30 are The fourth magnetoresistive element 40 and the fifth magnetoresistive element 50 are arranged so that their longitudinal directions are on the same straight line. The pinning directions of the pinning layers of the first magnetoresistive element 10 and the third to fifth magnetoresistive elements (30, 40, 50) are orthogonal to the longitudinal direction, and the first magnetoresistive element The direction of pinning of the third magnetoresistive element 30 with respect to 10 is reversed, and the direction of pinning of the fifth magnetoresistive element 50 with respect to the fourth magnetoresistive element 40 is reversed. Further, the pinning directions of the first magnetoresistive element 10 and the fifth magnetoresistive element 50 and the third magnetoresistive element 30 and the fourth magnetoresistive element 40 which are arranged diagonally are the same direction. Yes. Furthermore, the first magnetoresistive element 10 and the third magnetoresistive element 30, and the fourth magnetoresistive element 40 and the fifth magnetoresistive element 50 are arranged in parallel to each other. By arranging the first magnetoresistive element 10 and the third to fifth magnetoresistive elements (30, 40, 50) in this way, the first magnetoresistive element 10 and the environmental magnetic field in a certain direction The connection potential (V1) of the third magnetoresistive element 30 fluctuates, and the connection potential (V2) of the fourth magnetoresistive element 40 and the fifth magnetoresistive element 50 changes between the first magnetoresistive element 10 and the third magnetoresistive element 30. Since the same variation is exhibited with the opposite polarity to the connection potential (V1) of the magnetoresistive element 30, the input potential difference of the first differential operation circuit 211 can be increased. That is, the accuracy of the output of the first differential arithmetic circuit 211 that is output according to the environmental magnetic field is increased.

  FIG. 5 is a configuration diagram of the third magnetic field generation conductor 122 included in the second magnetic field detection unit 420 and the second magnetic field generation unit 120 according to the first embodiment. The second magnetic field detection unit 420 includes a fourth differential arithmetic circuit 221, a detection resistor 540, a second magnetoresistive element 20, and sixth to eighth magnetoresistive elements (60, 70, 80). Yes. Here, the second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80) are SV giant magnetoresistive elements, which are formed on a substrate, and have a free layer, a conductive layer, The pinned layer is laminated. An insulating film is formed on the second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80), and a third magnetic field generating conductor 122 is integrated with the insulating film on the upper part. It is formed. One end of the second magnetoresistive element 20 is connected to the first potential (Vc), the other end of the second magnetoresistive element 20 and the other end of the sixth magnetoresistive element 60 are connected, and the sixth magnetism One end of the resistance element 60 is connected to the third potential (Gnd). One end of the seventh magnetoresistive element 70 is connected to the first potential (Vc), the other end of the seventh magnetoresistive element 70 and the other end of the eighth magnetoresistive element 80 are connected, and the eighth magnetic One end of the resistance element 80 is connected to the third potential (Gnd). Here, the second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80) are arranged in the same plane, and the second magnetoresistive element 20 and the sixth magnetoresistive element 60 are The seventh magnetoresistive element 70 and the eighth magnetoresistive element 80 are arranged so that their longitudinal directions are on the same straight line. The pinning directions of the pinning layers of the second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80) are orthogonal to the longitudinal direction, and the second magnetoresistive element 20, the direction of pinning of the sixth magnetoresistive element 60 is opposite to that of the sixth magnetoresistive element 60, and the direction of pinning of the eighth magnetoresistive element 80 is opposite to that of the seventh magnetoresistive element 70. In addition, the pinning directions of the second magnetoresistive element 20 and the eighth magnetoresistive element 80, and the sixth magnetoresistive element 60 and the seventh magnetoresistive element 70 arranged diagonally are the same direction. Yes. Furthermore, the second magnetoresistive element 20 and the sixth magnetoresistive element 60, and the seventh magnetoresistive element 70 and the eighth magnetoresistive element 80 are arranged in parallel to each other. The third magnetic field generating conductor 122 becomes the first conductor portion 123 on the same straight line above the second magnetoresistive element 20 and the sixth magnetoresistive element 60, and the seventh magnetoresistive element 70 and the eighth The second magnetoresistive element 124 is also arranged on the same straight line as the upper part of the second magnetoresistive element 80, and a magnetic field in the opposite direction to the detected magnetic field is applied to the second magnetoresistive element 20 and the sixth to sixth magnetic resistance elements. It arrange | positions so that it may be given to eight magnetoresistive elements (60,70,80). Here, in the center between the first and second conductor parts (123, 124) having the same material, line width and length arranged in parallel, the linear third conductor part 125 is the first and second conductor parts 125. It exists in parallel with the second conductor part (123, 124). Further, one ends of the first and third conductor portions (123, 125) in the first direction are connected to each other, and the second and third conductor portions (124, 125) in the direction opposite to the first direction are connected. ) Are connected to each other. By arranging the second magnetoresistive element 20 and the sixth to eighth magnetoresistors (60, 70, 80) and the third magnetic field generating conductor 122 in this manner, the second magnetic resistance element 20 and the sixth magnetic field generating conductor 122 are arranged with respect to the detected magnetic field. The connection potential (V3) between the first magnetoresistance element 20 and the sixth magnetoresistance element 60 varies, and the connection potential (V4) between the seventh magnetoresistance element 70 and the eighth magnetoresistance element 80 is the second magnetoresistance. Since the connection potential (V3) between the element 20 and the sixth magnetoresistive element 60 exhibits the same fluctuation with the opposite polarity, the input potential difference of the fourth differential arithmetic circuit 221 can be increased. That is, the accuracy of the output of the fourth differential arithmetic circuit 221 output according to the detected magnetic field is increased. The output terminal of the fourth differential arithmetic circuit 221 has one end connected to the other end of the detection resistor 540 connected to the other end of the first conductor portion 123 of the third magnetic field generating conductor 122, and the third One end of the second conductor portion 124 of the magnetic field generating conductor 122 is connected to a third potential (GND).

  FIG. 6 is a structural diagram of the magnetic field detection device 3 according to the first embodiment. The mounting substrate 1a includes a first magnetic field detection unit 410 having the first differential operation circuit 211 shown in FIG. 4 and a second magnetic field detection unit 420 having the fourth differential operation circuit 221 shown in FIG. And the 3rd magnetic field generation | occurrence | production conductor 122 which the 2nd magnetic field generation part 120 has is mounted. Here, the first magnetic field generating conductor 111 is disposed apart from the first magnetoresistive element 10 and the third to fifth magnetoresistive elements (30, 40, 50). The first solenoid coil is disposed so as to surround the third to fifth magnetoresistive elements (30, 40, 50), and the second magnetic field generating conductor 121 includes the second magnetoresistive element 20 and the sixth magnetoresistive element. The eighth magnetoresistive element (60, 70, 80) is disposed apart from the second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80). The second solenoid coil. The first and second solenoid coils have the same number of turns, winding direction, material, width, and length. The first and second solenoid coils are arranged on both end sides of the mounting substrate 1a, respectively, so that the center lines of the first and second solenoid coils are parallel to each other. Here, the center line is a straight line obtained by extending the center of the solenoid coil when the solenoid coil is viewed from the length direction. The first magnetic field generation conductor 111 included in the first magnetic field generation unit 110 generates a first feedback current magnetic field in a direction opposite to the environmental magnetic field by using the first magnetoresistance element 10 and the third to fifth magnetoresistance elements (30 , 40, 50), and the second magnetic field generating conductor 121 included in the second magnetic field generation unit 120 applies a second current magnetic field in the direction opposite to the environmental magnetic field to the second magnetoresistive. Arranged to be applied to the element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80). One end of the first magnetic field generating conductor 111 and the output end of the first differential arithmetic circuit 211 are connected, the other end of the first magnetic field generating conductor 111 and one end of the second magnetic field generating conductor 121 are connected, The other end of the second magnetic field generating conductor 121 is connected to a third potential (Gnd). Therefore, the first feedback current flowing through the first magnetic field generating conductor 111 and the second current flowing through the second magnetic field generating conductor 121 are the same current. Here, since the winding directions of the first and second solenoid coils are the same, the magnetic field at the center line of the first solenoid coil of the first feedback current magnetic field and the second solenoid coil of the second current magnetic field The magnetic field of the center line is substantially in the same direction.

  As described above, the first magnetic field generating conductor 111 and the second magnetic field generating conductor 121 are solenoid-like coils, and the first magnetoresistive element disposed apart from the first magnetic field generating conductor 111. 10 and the third to fifth magnetoresistive elements (30, 40, 50) are arranged inside the first solenoid coil which is the first magnetic field generating conductor 111 and are separated from the second magnetic field generating conductor 121. The arranged second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80) are arranged inside the second solenoid coil which is the second magnetic field generating conductor 121. Further, the first magnetoresistive element 10 and the third to fifth magnetoresistive elements (30, 40, 50) are substantially equal from the center of the first magnetic field generating conductor 111, that is, from the center line of the first solenoid coil. The first magnetoresistive element 10 and the third magnetoresistive element 30, the fourth magnetoresistive element 40 and the fifth magnetoresistive element 50 are disposed at a distance, and the first magnetic field generating conductor 111 is the first magnetic field generating conductor 111. The first magnetoresistive element 10, the fourth magnetoresistive element 40, the third magnetoresistive element 30, and the fifth magnetoresistive element are axisymmetric with respect to a first straight line (not shown) passing through the center of the solenoid coil. The magnetoresistive element 50 is symmetrical with respect to a second straight line (not shown) orthogonal to a first straight line (not shown) passing through the center of the first solenoid coil that is the first magnetic field generating conductor 111. It is preferable. The second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80) are substantially equidistant from the center of the second magnetic field generating conductor 121, that is, the center line of the second solenoid coil. And a second solenoid coil in which the second magnetoresistive element 20, the sixth magnetoresistive element 60, the seventh magnetoresistive element 70, and the eighth magnetoresistive element 80 are the second magnetic field generating conductor 121. And a second magnetoresistive element 20, a seventh magnetoresistive element 70, a sixth magnetoresistive element 60, and an eighth magnetoresistive element. The element 80 may be axisymmetric with respect to a fourth straight line (not shown) orthogonal to a third straight line (not shown) passing through the center of the second solenoid coil that is the second magnetic field generating conductor 121. preferable. Furthermore, the surface on which the first magnetoresistive element 10 and the third to fifth magnetoresistive elements (30, 40, 50) are arranged and the second and sixth to eighth magnetoresistive elements (60, 70, 80) is preferably parallel so that the longitudinal directions of the first to eighth magnetoresistive elements (10 to 80) face the same direction. In the first embodiment, the second straight line and the center line passing through the center of the first solenoid coil substantially coincide with each other, and the fourth straight line and the center line passing through the center of the second solenoid coil substantially coincide with each other. It has become. With such an arrangement, the first to eighth magnetoresistive elements (10 to 80) change in resistance with respect to the magnetic field orthogonal to the longitudinal direction. It is possible to increase the output of each bridge circuit shown in FIG. In addition, since the first and second solenoid coils are individually arranged, the design is facilitated as compared with the integrated solenoid coil. In addition, the coil itself can be made smaller than the integrated solenoid coil.

  When the first magnetic field detection unit 410 detects an environmental magnetic field, the connection potential (V1) between the first magnetoresistance element 10 and the third magnetoresistance element 30, the fourth magnetoresistance element 40, and the fifth magnetoresistance. A potential difference is generated in the connection potential (V2) of the element 50, and the first differential operation circuit 211 passes an output corresponding to the potential difference, that is, a first feedback current to the first magnetic field generating conductor 111, and an environmental magnetic field is generated. A magnetic field in the direction opposite to the environmental magnetic field is generated so as to reduce. As a result, the potential difference between the pair of input terminals of the first differential arithmetic circuit 211 becomes zero, and the first feedback current corresponding to the environmental magnetic field flows to the second magnetic field generating conductor 121 as the second current.

  Since the environmental magnetic field that affects the first magnetic field detection unit 210 and the second magnetic field detection unit 420 is considered to be substantially uniform, the magnetic field generated by the second current in the second magnetic field generation conductor 121 changes the environmental magnetic field. By reducing, the second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80) can detect the detection magnetic field in a state where the environmental magnetic field is reduced.

  When the detected magnetic field is detected by the second magnetic field detector 420, the connection potential (V3) of the second magnetoresistive element 20 and the sixth magnetoresistive element 60, the seventh magnetoresistive element 70, and the eighth magnetoresistive. A potential difference is generated in the connection potential (V4) of the element 80, and the fourth differential operation circuit 221 causes the second feedback current to flow to the detection resistor 540 and the third magnetic field generating conductor 122 so that the potential difference becomes zero. The third magnetic field generating conductor 122 generates a magnetic field opposite to the detected magnetic field so as to reduce the detected magnetic field.

  Accordingly, the potential difference between the pair of input terminals of the fourth differential arithmetic circuit 221 is zero, and the second feedback current corresponding to the detected magnetic field is used as a voltage value at the connection point between the detection resistor 540 and the fourth arithmetic circuit 221. It becomes possible to detect.

  Since the output of the first differential circuit 211 forms a current feedback loop for flowing a current for generating a magnetic field for reducing the environmental magnetic field to the first magnetic field generating conductor 111, the first magnetic field detecting unit The resistance change ΔR of the magnetoresistive element (10, 30, 40, 50) included in 410 is controlled so that the output of the first differential circuit 211 is always zero with respect to the environmental magnetic field. Output fluctuation (temperature drift) due to temperature in R can be suppressed. In addition, since an equivalent current flows through the second magnetic field generation conductor 121, the second magnetic field detection unit 420 also includes a second current magnetic field that reduces the environmental magnetic field generated by the second magnetic field generation conductor 121. The output fluctuation (temperature drift) due to the temperature of the resistance change ΔR of the element (20, 60, 70, 80) is suppressed. That is, the output of the fourth differential arithmetic circuit 221 can detect the detected magnetic field in a state where the output fluctuation (temperature drift) due to the temperature of the resistance change ΔR of the magnetoresistive element in the environmental magnetic field is suppressed. In addition, since a current feedback loop is formed in which the second feedback current flows through the third magnetic field generating conductor 122 even in the detected magnetic field, the magnetoresistive elements (20, 60, 70,. It is possible to suppress the output fluctuation (temperature drift) due to the temperature of the resistance change ΔR of 80).

  Since the magnetic field generated by the second current in the second magnetic field generating conductor 121 reduces the environmental magnetic field, the second magnetoresistive element 20 and the sixth to eighth magnetoresistive elements (60, 70, 80) are the environment. Since the detection magnetic field can be detected in a state where the magnetic field is reduced, there is no need for an arithmetic circuit for removing the environmental magnetic field, the number of parts can be reduced, the cost can be reduced, and the size can be reduced.

  The present invention can be applied to a magnetic field detection device that detects a magnetic field such as a minute detection magnetic field, a measurement device that uses the magnetic field detection device, and an electric device.

1 2 3 Magnetic field detection device 1a Mounting board 10 20 Magnetic field detection element 110 120 Magnetic field generation unit 111 121 122 Magnetic field generation conductor 123 124 125 Conductor unit 210 220 Differential operation unit 211 221 Differential operation circuit 410 420 Magnetic field detection unit 510 520 Resistance 530 540 Detection resistance

Claims (2)

A first magnetic field generator having a first coil;
A first output of the first magnetic field detection element corresponding to the first magnetic field detection element and the environmental magnetic field is input, and a first feedback current magnetic field in a direction opposite to the environmental magnetic field is applied to the first magnetic field detection element. A first magnetic field detection unit having a first differential operation unit for supplying a first feedback current to the first coil to be provided by the first magnetic field generation unit;
A second magnetic field generator having a second coil through which a second current corresponding to the first feedback current flows;
A second magnetic field detection unit having a second magnetic field detection element,
The second coil applies a magnetic field in a direction opposite to the environmental magnetic field according to the second current to the second magnetic field detection element,
The second magnetic field detection unit detects a detection magnetic field, and a center line of the first coil and a center line of the second coil are parallel and substantially coincide with each other, and the first magnetic field detection element is The magnetic field detection device is arranged inside the first coil, and the second magnetic field detection element is arranged inside the second coil . The magnetic field detection device according to claim 1, wherein the first and second magnetic field detection elements are magnetoresistive elements.

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